Reduced pressure indicator for a reduced pressure source

ABSTRACT

A reduced pressure apparatus includes a first casing portion and a second casing portion slidably coupled to the first casing portion such that the first casing portion is compressible into a plurality of positions relative to the second casing portion. The plurality of positions includes a fully compressed position and a fully uncompressed position. An indicator is disposed on at least one of the first casing portion and the second casing portion, the indicator being exposed when the first casing portion is in the fully uncompressed position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/434,579, filed May 1, 2009, which claims the benefit of U.S.Provisional Application No. 61/050,107, filed May 2, 2008, and which isa continuation-in-part application of U.S. patent application Ser. No.11/974,534, filed Oct. 15, 2007, which claims the benefit U.S.Provisional Application No. 60/851,494, filed Oct. 13, 2006; thisapplication is a continuation-in-part application of U.S. patentapplication Ser. No. 12/069,262, filed Feb. 8, 2008, which claims thebenefit U.S. Provisional Application No. 60/900,555, filed Feb. 9, 2007.All of the above-referenced applications are hereby incorporated byreference.

BACKGROUND

1. Field of the Invention

The present invention relates generally to the field of tissuetreatment, and more specifically to a system and method for applyingreduced pressure at a tissue site.

2. Description of Related Art

Clinical studies and practice have shown that providing a reducedpressure in proximity to a tissue site augments and accelerates thegrowth of new tissue at the tissue site. The applications of thisphenomenon are numerous, but one particular application of reducedpressure has involved treating wounds. This treatment (frequentlyreferred to in the medical community as “negative pressure woundtherapy,” “reduced pressure therapy,” or “vacuum therapy”) provides anumber of benefits, including migration of epithelial and subcutaneoustissues, improved blood flow, and micro-deformation of tissue at thewound site. Together these benefits result in increased development ofgranulation tissue and faster healing times. Typically, reduced pressureis applied to tissue through a porous pad or other manifold device. Theporous pad contains cells or pores that are capable of distributingreduced pressure to the tissue and channeling fluids that are drawn fromthe tissue. The porous pad may be incorporated into a dressing havingother components that facilitate treatment.

SUMMARY

The problems presented by existing reduced pressure systems are solvedby the systems and methods of the illustrative embodiments describedherein. In one illustrative embodiment, a reduced pressure apparatusincludes a first casing portion and a second casing portion, the secondcasing portion being slidably coupled to the first casing portion suchthat the first casing portion is compressible into a plurality ofpositions relative to the second casing portion. The plurality ofpositions includes a fully compressed position and a fully uncompressedposition. An indicator is disposed on at least one of the first casingportion and the second casing portion, the indicator being exposed whenthe first casing portion is in the fully uncompressed position.

In another embodiment, a reduced pressure therapy system foradministering reduced pressure treatment to a tissue site includes amanifold adapted to be positioned at the tissue site, a reduced pressuresource in fluid communication with the manifold to deliver a reducedpressure to the manifold, and a sealing member adapted to cover thetissue site to form a sealed space between the sealing member and thetissue site, the sealed space being in fluid communication with thereduced pressure source. The reduced pressure source includes a topcasing portion and a bottom casing portion, the bottom casing portionbeing slidably coupled to the top casing portion such that the topcasing portion is positionable in a plurality of positions relative tothe bottom casing portion. The plurality of positions includes a fullycompressed position, a fully uncompressed position, and a plurality ofintermediate positions between the fully compressed position and thefully uncompressed position. The reduced pressure source is operable todeliver the reduced pressure when the top casing portion is in the fullycompressed position. The reduced pressure source further includes anindicator disposed on at least one of the top casing portion and thebottom casing portion. The indicator is exposed when the top casingportion is in at least one of the plurality of intermediate positions.

In yet another embodiment, a reduced pressure apparatus includes asubstantially cylindrical top casing portion and a substantiallycylindrical bottom casing portion. The substantially cylindrical bottomcasing portion has a larger diameter than the substantially cylindricaltop casing portion. The substantially cylindrical top casing portion isslidably received by the substantially cylindrical bottom casing portionsuch that the substantially cylindrical top casing portion ispositionable in a plurality of positions relative to the substantiallycylindrical bottom casing portion. The plurality of positions includes afully compressed position, a fully uncompressed position, and aplurality of intermediate positions between the fully compressedposition and the fully uncompressed position. The reduced pressureapparatus is operable to deliver a reduced pressure as the substantiallycylindrical top casing portion moves from the fully compressed positionto the fully uncompressed position. The reduced pressure apparatusfurther includes a color strip disposed on the substantially cylindricaltop casing portion such that the color strip is exposed when thesubstantially cylindrical top casing portion is in the fullyuncompressed position and is obscured when the substantially cylindricaltop casing portion is in the fully compressed position.

Other objects, features, and advantages of the illustrative embodimentswill become apparent with reference to the drawings and detaileddescription that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of an apparatus for applying reducedpressure at a tissue site in accordance with an illustrative embodiment;

FIG. 2 illustrates a cross-sectional view of an apparatus for applyingreduced pressure at a tissue site in accordance with an illustrativeembodiment;

FIG. 3 illustrates a perspective view of a compressible pump in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 4 illustrates a cross-sectional view of a filter housing in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 5 illustrates a cross-sectional view of an interlocking seal in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 6 illustrates a cross-sectional view of an interlocking seal in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 7 illustrates a cross-sectional view of an outlet valve in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 8 illustrates a cross-sectional view of a connection joint in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 9 illustrates a perspective view of outlet valves on a compressiblepump in an apparatus for applying reduced pressure at a tissue site inaccordance with an illustrative embodiment;

FIG. 10 illustrates a cross-sectional view of an outlet valve in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 11 illustrates a cross-sectional view of an outlet valve in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 12 illustrates a cross-sectional view of an outlet valve in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 13 illustrates a perspective view of an outlet valve in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 14 illustrates a perspective view of an apparatus for applyingreduced pressure at a tissue site in accordance with an illustrativeembodiment;

FIG. 15 illustrates a perspective view of two compressible pumps in anapparatus for applying reduced pressure at a tissue site in accordancewith an illustrative embodiment;

FIG. 16 illustrates a perspective view of an apparatus for applyingreduced pressure at a tissue site in accordance with an illustrativeembodiment;

FIG. 17 a illustrates a perspective view of an apparatus for determininga reduced pressure associated with a reduced pressure source inaccordance with an illustrative embodiment;

FIG. 17 b shows a side view of the apparatus of FIG. 17 a in thecompressed position;

FIG. 17 c shows a reduced pressure therapy system that utilizes theapparatus shown in FIG. 17 a;

FIG. 18 illustrates a perspective view of an apparatus for determining areduced pressure associated with a reduced pressure source in accordancewith an illustrative embodiment; and

FIG. 19 illustrates a flowchart illustrating a process for applyingreduced pressure at a tissue site in accordance with an illustrativeembodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

In the following detailed description of the illustrative embodiments,reference is made to the accompanying drawings that form a part hereof.These embodiments are described in sufficient detail to enable thoseskilled in the art to practice the invention, and it is understood thatother embodiments may be utilized and that logical structural,mechanical, electrical, and chemical changes may be made withoutdeparting from the spirit or scope of the invention. To avoid detail notnecessary to enable those skilled in the art to practice the embodimentsdescribed herein, the description may omit certain information known tothose skilled in the art. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of thepresent invention is defined only by the appended claims.

The term “reduced pressure” as used herein generally refers to apressure less than the ambient pressure at a tissue site that is beingsubjected to treatment. In most cases, this reduced pressure will beless than the atmospheric pressure at which the patient is located.Alternatively, the reduced pressure may be less than a hydrostaticpressure associated with tissue at the tissue site. Although the terms“vacuum” and “negative pressure” may be used to describe the pressureapplied to the tissue site, the actual pressure reduction applied to thetissue site may be significantly less than the pressure reductionnormally associated with a complete vacuum. Reduced pressure mayinitially generate fluid flow in the area of the tissue site. As thehydrostatic pressure around the tissue site approaches the desiredreduced pressure, the flow may subside, and the reduced pressure is thenmaintained. Unless otherwise indicated, values of pressure stated hereinare gauge pressures. Similarly, references to increases in reducedpressure typically refer to a decrease in absolute pressure, whiledecreases in reduced pressure typically refer to an increase in absolutepressure.

The term “tissue site” as used herein refers to a wound or defectlocated on or within any tissue, including but not limited to, bonetissue, adipose tissue, muscle tissue, neural tissue, dermal tissue,vascular tissue, connective tissue, cartilage, tendons, or ligaments.The term “tissue site” may further refer to areas of any tissue that arenot necessarily wounded or defective, but are instead areas in which itis desired to add or promote the growth of, additional tissue. Forexample, reduced pressure tissue treatment may be used in certain tissueareas to grow additional tissue that may be harvested and transplantedto another tissue location.

Reduced pressure treatment systems are often applied to large, highlyexudating wounds present on patients undergoing acute or chronic care,as well as other severe wounds that are not readily susceptible tohealing without application of reduced pressure. Low-severity woundsthat are smaller in volume and produce less exudate have generally beentreated using advanced dressings instead of reduced pressure treatment.

Currently, the use of reduced pressure treatment is not considered aviable or affordable option for low-severity wounds due to the manpowerrequired to monitor and change system components, the requirement fortrained medical personnel overseeing treatment, and the high cost oftreatment. For example, the complexity of current reduced pressuretreatment systems precludes a person with little or no specializedknowledge from administering such treatment to oneself or others. Thesize and power consumption characteristics of current reduced pressuretreatment systems also limit the mobility of both the treatment systemand the person to whom the treatment is being applied. Also, the highcost of current reduced pressure treatment systems can preclude theaccessibility of such treatment systems to some users. Current reducedpressure treatment systems are also typically non-disposable after eachtreatment. In addition, users with little or no specialized knowledgehave no easy and convenient way to determine whether a manually actuatedreduced pressure source requires attention to maintain a desired reducedpressure level at a tissue site.

Referring to FIG. 1, a reduced pressure treatment system 100 accordingto an illustrative embodiment applies reduced pressure to a tissue site105 to promote the drainage of exudate and other liquids from tissuesite 105, as well as stimulate the growth of additional tissue. Reducedpressure treatment system 100 includes a pump 102. Pump 102 includes avariable volume chamber 110 and a fixed volume chamber 115, which arecoupled to one another via filter housing 120. Variable volume chamber110 has a variable volume that is affected by the compression ofcompressible pump along an axis 122. Variable volume chamber 110 mayalso be compressed along other axes.

Variable volume chamber 110 may be manually-actuated. That is, thecompression of variable volume chamber 110 may be performed by anyliving organism. For example, variable volume chamber 110 may bemanually pushed, squeezed, or otherwise compressed by a human hand,finger, or other limb. Variable volume chamber 110 may be any type ofmanually-actuated chamber. For example, variable volume chamber 110 maybe a compressible bellows having corrugated side walls.

In one embodiment, variable volume chamber 110 is compressible into, aplurality of positions, each of which may be representative of adifferent volume for variable volume chamber 110. For example, variablevolume chamber 110 has the greatest volume when the variable volumechamber 110 is in a fully uncompressed position. In a fully compressedposition, variable volume chamber 110 has the smallest volume. Variablevolume chamber 110 may also have a plurality of intermediate positionsbetween the fully uncompressed position and the fully compressedposition, including partially compressed or partially uncompressedpositions.

Variable volume chamber 110 includes an outlet valve 124. Outlet valve124 permits the passage of gas, such as air, out of variable volumechamber 110. Outlet valve 124 also prevents gas from entering variablevolume chamber 110. Thus, when the volume of variable volume chamber 110is reduced due to the compression of compressible pump from anuncompressed position to a compressed position, gas is forced out ofvariable volume chamber 110. Outlet valve 124 may be any type of valvecapable of permitting the passage of gas out of variable volume chamber110 while preventing the passage of gas into variable volume chamber110. A non-limiting example of outlet valve 124 is an umbrella valve,duckbill valve, ball valve, diaphragm valve, and any type of one-wayvalve.

Although FIG. 1 shows variable volume chamber 110 as having a singleoutlet valve 124, variable volume chamber 110 may have any number ofoutlet valves. Also, although FIG. 1 shows outlet valve 124 at the endportion of variable volume chamber 110, outlet valve 124 may be locatedon any portion of variable volume chamber 110, such as the side walls ofvariable volume chamber 110. In one embodiment, outlet valve 124 islocated at an end of variable volume chamber 110 that is opposite of theend at which filter housing 120 is located. Additional details regardingoutlet valve 124 will be provided in FIGS. 2, 7, and 9-13 below.

Fixed volume chamber 115 is capable of containing any fluid, such asgases and liquids, as well as fluids that contain solids. For example,fixed volume chamber 115 may contain exudates from tissue site 105. Inone example, fixed volume chamber 115 has a substantially fixed volume.Fixed volume chamber 115 may be made of any material capable ofproviding fixed volume chamber 115 with a substantially fixed volume,including metal, plastic, or hardened rubber.

Fixed volume chamber 115 includes side walls 125 and 127, which arecoupled to an end wall 130. Side walls 125 and 127 may be contiguouslyformed with an end wall 130 such that no joint exists between side walls125 and 127 and end wall 130. In addition, side walls 125 and 127 may bewelded, screwed, glued, bolted, air-lock sealed, or snapped onto endwall 130.

Fixed volume chamber 115 is coupled to variable volume chamber 110 by afilter housing 120. Fixed volume chamber 115 and variable volume chamber110 may be coupled to filter housing 120 in a variety of ways. Forexample, fixed volume chamber 115 or variable volume chamber 110 may bewelded, screwed, glued, bolted, air-lock sealed, or snapped onto filterhousing 120. Fixed volume chamber 115 or variable volume chamber 110 mayalso be part of the same material as filter housing 120, therebyeliminating the need for joints or seals between fixed volume chamber115 and filter housing 120. In another example, variable volume chamber110 may be sealed to filter housing 120 using an interlocking seal.Additional details regarding the coupling of filter housing 120 withfixed volume chamber 115 or variable volume chamber 110 are describedbelow in FIGS. 2, 5, 6, 10-13, and 14.

Filter housing 120 is capable of including one or more filters. In oneembodiment, filter housing 120 includes a hydrophobic filter thatprevents liquid from entering variable volume chamber 110 from fixedvolume chamber 115. However, as described below, the hydrophobic filterpermits the passage of air such that reduced pressure may be transferredfrom variable volume chamber 110 to fixed volume chamber 115. Filterhousing 120 may also include an odor filter that restrains or preventsthe transmission of odor from fixed volume chamber 115 to variablevolume chamber 110. Additional details regarding the hydrophobic filterand odor filter will be provided in FIGS. 2, 4, and 14 below.

Fixed volume chamber 115 is coupled to a delivery tube 135 via an inletvalve 140. Inlet valve 140 is located at an inlet point 143. Inlet valve140 permits the passage of fluid, such as exudate, into fixed volumechamber 115 at inlet point 143. Inlet valve 140 also restrains thepassage of fluid out of fixed volume chamber 115 at inlet point 143.Inlet valve 140 may be any type of valve, such as an umbrella valve,duck bill valve, or a combination thereof.

Inlet valve 140 may be located at the center of end wall 130. AlthoughFIG. 1 shows fixed volume chamber 115 as having a single inlet valve140, fixed volume chamber 115 may have any number of inlet valves. Also,although FIG. 1 shows inlet valve 140 at end wall 130 of fixed volumechamber 115, inlet valve 140 may be located on any portion of fixedvolume chamber 115, such as side walls 125 and 127 of fixed volumechamber 115. Additional details regarding inlet valve 140 will beprovided in FIGS. 2 and 17 below.

Delivery tube 135 is any tube through which a fluid may flow. Deliverytube 135 may be made from any material, and may include one or morepaths or lumens through which fluid may flow. For example, delivery tube135 may include two lumens. In this example, one lumen may be used forthe passage of exudate from tissue site 105 to fixed volume chamber 115.The other lumen may be used to deliver fluids, such as air,antibacterial agents, antiviral agents, cell-growth promotion agents,irrigation fluids, or other chemically active agents, to tissue site105. The fluid source from which these deliverable fluids originate isnot shown in FIG. 1.

Delivery tube 135 may be fixedly attached to fixed volume chamber 115 atinlet point 143. Also, delivery tube 135 may be detachable from fixedvolume chamber 115 at inlet point 143. For example, delivery tube 135may be snapped onto fixed volume chamber 115. Additional detailsregarding the coupling the delivery tube 135 to fixed volume chamber 115will be provided in FIGS. 2 and 16-18 below.

The opposite end of delivery tube 135 is coupled to a manifold 145.Manifold 145 may be a biocompatible, porous material that is capable ofbeing placed in contact with tissue site 105 and distributing reducedpressure to the tissue site 105. Manifold 145 may be made from foam,gauze, felted mat, or any other material suited to a particularbiological application. Manifold 145 may include a plurality of flowchannels or pathways to facilitate distribution of reduced pressure orfluids to or, from the tissue site.

Manifold 145 may be secured to tissue site 105 using a sealing member150. Sealing member 150 may be a cover that is used to secure manifold145 at tissue site 105. While sealing member 150 may be impermeable orsemi-permeable, in one example sealing member 150 is capable ofmaintaining a reduced pressure at tissue site 105 after installation ofthe sealing member 150 over manifold 145. Sealing member 150 may be aflexible drape or film made from a silicone based compound, acrylic,hydrogel or hydrogel-forming material, or any other biocompatiblematerial that includes the impermeability or permeabilitycharacteristics desired for tissue site 105.

In one embodiment, sealing member 150 is configured to provide a sealedconnection with the tissue surrounding manifold 145 and tissue site 105.The sealed connection may be provided by an adhesive positioned along aperimeter of sealing member 150 or on any portion of sealing member 150to secure sealing member 150 to manifold 145 or the tissue surroundingtissue site 105. The adhesive may be pre-positioned on sealing member150 or may be sprayed or otherwise applied to sealing member 150immediately prior to installing sealing member 150.

In one embodiment, delivery tube 135 is coupled to manifold 145 via aconnection member 155. Connection member 155 permits the passage offluid from manifold 145 to delivery tube 135, and vice versa. Forexample, exudates collected from tissue site 105 using manifold 145 mayenter delivery tube 135 via connection member 155. In anotherembodiment, reduced pressure treatment system 100 does not includeconnection member 155. In this embodiment, delivery tube 135 may beinserted directly into sealing member 150 such that an end of deliverytube 135 is adjacent to manifold 145.

Reduced pressure treatment system 100 may also include a pressurefeedback system 160. Pressure feedback system 160 may be operablyassociated with the other components of reduced pressure treatmentsystem 100 to provide information to a user of reduced pressuretreatment system 100 that indicates a relative or absolute amount ofpressure that is being delivered to tissue site 105. Pressure feedbacksystem 160 allows a user to accurately track the amount of reducedpressure that is being generated by reduced pressure treatment system100. Non-limiting examples of pressure feedback systems include popvalves that activate when the reduced pressure rises above a selectedvalue, low power electronic indicators powered by miniature cells, dialindicators that indicate specific pressure values that are being appliedto the tissue site, deflection pop valves, polymers with variousdeflection characteristics, and films that move relative to one anotherto produce visual identifiers indicating the relative or absolutepressure values being generated by reduced pressure treatment system100. An example of a film-based system may include a yellow filmanchored to a first part of pump 102 that is capable of movementrelative to a blue film anchored to a second part. When the first andsecond parts are moved relative to one another to apply a reducedpressure, the yellow and blue films overlap to create a green indicator.As the pressure increases and the films move away from one another, theloss of the green color indicates that the pressure has increased (i.e.,more reduced pressure needs to be applied).

Also, although pressure feedback system 160 is shown as separate fromthe other components of reduced pressure treatment system 100, pressurefeedback system 160 may form an integral part of any of the componentsof reduced pressure treatment system 100. Additional details regardingpressure feedback system 160 will be described in FIGS. 14 and 16 below.In addition to the above-mentioned components and systems, reducedpressure treatment system 100 may include valves, regulators, switches,and other electrical, mechanical, and fluid components to facilitateadministration of reduced pressure treatment to tissue site 105.

A desiccant or absorptive material may be disposed within fixed volumechamber 115 to trap or control fluid once the fluid has been collected.In the absence of fixed volume chamber 115, a method for controllingexudate and other fluids may be employed in which the fluids, especiallythose that are water soluble, are allowed to evaporate from manifold145.

In one embodiment, variable volume chamber 110 is moved from anuncompressed position to a compressed position, thereby decreasing thevolume of variable volume chamber 110. As a result, gas is expelled fromvariable volume chamber 110 through outlet valve 124. Because gas cannotenter variable volume chamber 110 via outlet valve 124, gas cannot entervariable volume chamber 110 from a surrounding space 165. Thus, asvariable volume chamber 110 expands from the compressed position to theuncompressed position, gas is transferred from fixed volume chamber 115to variable volume chamber 110. The movement of variable volume chamber110 from a compressed position to an uncompressed position may be causedby any expansion force. In an illustrative example in which the sidewalls of variable volume chamber 110 are corrugated side walls, theexpansion force may be caused by the tendency of the corrugations in thecorrugated side walls to move away from one another and thereby returnvariable volume chamber 110 to the uncompressed position. The expansionforce may also be caused by an independent biasing member, such as aspring or foam component, that is located within or outside of variablevolume chamber 110. In another example, the resiliency of non-corrugatedside walls of variable volume chamber 110 may be used to move variablevolume chamber 110 to an uncompressed position.

Liquid, such as exudate, is prevented from being transferred from fixedvolume chamber 115 to variable volume chamber 110 by a filter, such as ahydrophobic filter, in filter housing 120. Because fixed volume chamber115 is sealed from surrounding space 165, a reduced pressure isgenerated in fixed volume chamber 115 as variable volume chamber 110expands from the compressed position to the uncompressed position. Thisreduced pressure is than transferred to tissue site 105 via deliverytube 135 and manifold 145. This reduced pressure may be maintained attissue site 105 using sealing member 150.

This process of moving variable volume chamber 110 from an uncompressedto a compressed position, and vice versa, in order to achieve a reducedpressure at tissue site 105 may be repeated. In particular, variablevolume chamber 110 may undergo multiple compression/expansion cyclesuntil fixed volume chamber 115 is filled with liquid, such as exudate,from tissue site 105. The multi-chamber configuration of pump 102, whichincludes variable volume chamber 110 and fixed volume chamber 115,permits compressible pump to be compressed regardless of the amount ofliquid in fixed volume chamber 115. As a result, the desired pressuremay be achieved during the compression/expansion cycles regardless ofthe amount of liquid in fixed volume chamber 115.

Referring to FIG. 2, pump 200, which is a non-limiting example of pump102 in FIG. 1, is shown in accordance with an illustrative embodiment.Pump 200 may be used as a substitute for pump 102 in FIG. 1.

Pump 200 includes a compressible bellows 210. Compressible bellows 210is a non-limiting example of variable volume chamber 110 in FIG. 1.Compressible bellows 210 may be moved into a plurality of positions,such as an uncompressed position and a compressed position. Compressiblebellows 210 is formed from corrugated side walls with corrugations 212.Corrugations 212 may move toward and away from one another, resulting ina compression and expansion of compressible bellows 210. For example,compressible bellows 210 may move from a compressed position to anuncompressed position due to the expansion force provided by a decreasein the linear density of corrugations 212. This expansion force may beprovided by the tendency of corrugations 212 to move away from oneanother.

In addition, compressible bellows 210 may be composed of any materialthat allows the compression and expansion of compressible bellows 210.The expansion force provided by the corrugated side walls may depend onthe material from which compressible bellows 210 is composed. Thus, theamount of pressure provided by compressible bellows 210 to a tissuesite, such as tissue site 105 in FIG. 1, may also depend on the materialfrom which compressible bellows 210 is composed. Factors that may affectthe amount of pressure provided by compressible bellows 210 includematerial hardness, elasticity, thickness, resiliency, and permeability.A material may also be selected based on the degree of pressure decayexperienced by pump 200 as compressible bellows 210 moves from acompressed position to an uncompressed position. The expansion forceprovided by the corrugated side walls may also depend on the design ofcompressible bellows 210. The variance in cross-section of compressiblebellows 210 affects the amount of obtainable reduced pressure as well asthe input input pressure required to initiate compressible bellows 210.

In one non-limiting example, compressible bellows 210 is composed ofShore 65 A. Shore 65 A may be capable of providing between 125 and 150mm Hg of pressure. These levels of pressure may also be capable of beingmaintained for at least six hours. For higher pressures, hardermaterials, such as Shore 85 A, may be used. By varying the material fromwhich compressible bellows 210 is composed, pressures of 250 mm Hg, aswell as pressures above 400 mm Hg, may by achieved using compressiblebellows 210.

Although compressible bellows 210 is shown to have a circularcross-sectional shape, compressible bellows 210 may have anycross-sectional shape. For example, the cross sectional shape ofcompressible bellows 210 may be an oval or polygon, such as a pentagon,hexagon, or octagon.

Compressible bellows 210 includes outlet valve 224. Outlet valve 224 isa non-limiting example of outlet valve 124 in FIG. 1. Gas exitscompressible bellows 210 via outlet valve 224 in response to a movementof compressible bellows 210 from an uncompressed position to acompressed position. Outlet valve 224 may be located anywhere oncompressible bellows 210. For example, outlet valve 224 may be locatedon an end of compressible bellows 210 that is opposite of the end atwhich filter housing 220 is located. Outlet valve 224 may also becentrally disposed on an end wall of compressible bellows 210. Thedirectional flow of the gas from compressible bellows 210 is indicatedby arrows 226. Outlet valve 224 prevents gas from entering compressiblebellows 210. In FIG. 2, outlet valve 224 is an umbrella valve, althoughoutlet valve 224 may be any type of valve. Additional details regardingoutlet valve 224 are described in FIG. 7 below.

As indicated by dotted lines 228, compressible bellows 210 is coupled tofilter housing 220. Compressible bellows 210 may be welded, screwed,glued, bolted, air-lock sealed, or snapped onto filter housing 220.Additional details regarding the coupling between compressible bellows210 and filter housing 220 are described in FIGS. 5 and 6 below.

Filter housing 220 is a non-limiting example of filter housing 120 inFIG. 1. Filter housing may be composed of any material, such as plastic,metal, rubber, or any other material capable of holding one or morefilters. Filter housing 220 contains an odor filter 231, which isattached to filter housing 220 as indicated by dotted lines 236. Odorfilter 231 may be screwed, glued, bolted, air-lock sealed, snapped onto,or otherwise placed adjacent to filter housing 220. Also, filter housing220 may include a groove into which odor filter 231 is placed.

Odor filter 231 restrains or prevents the transmission of odor fromfixed volume chamber 215 to compressible bellows 210. Such odor may bethe result of exudate or other liquid contained in fixed volume chamber215. In one embodiment, odor filter 231 is a carbon odor filter. In thisembodiment, the carbon odor filter may include charcoal. Although FIG. 2depicts odor filter 231 as a having a flattened shape, odor filter 231may have any shape capable of restraining or preventing the transmissionof odor from fixed volume chamber 215 to compressible bellows 210. Forexample, odor filter 231 may have circular, ovular, or polygonal diskshape.

Filter housing 220 also includes a hydrophobic filter 234, which isattached to filter housing 220 as indicated by dotted lines 238.Hydrophobic filter 234 may be screwed, glued, bolted, air-lock sealed,snapped onto, ultrasonically welded, or otherwise placed adjacent tofilter housing 220. In one example, odor filter 231 is sandwichedbetween filter housing 220 and hydrophobic filter 234. In the example inwhich hydrophobic filter 234 is secured to filter housing 220, odorfilter 231 may be secured as a result of being sandwiched between filterhousing 220 and hydrophobic filter 234. Odor filter 231 and hydrophobicfilter 234 may be coupled to a side of filter housing 220 that is nearerto fixed volume chamber 215, as shown in FIG. 2.

Hydrophobic filter 234 prevents liquid, such as exudate, from enteringcompressible bellows 210. However, hydrophobic filter 234 allows thepassage of gas, such as air, such that reduced pressure may betransferred from compressible bellows 210 and fixed volume chamber 215.Hydrophobic filter 234 may be composed from any of a variety ofmaterials, such as expanded polytetrafluoroethene.

Pump 200 includes fixed volume chamber 215. Fixed volume chamber 215 isa non-limiting example of fixed volume chamber 115 in FIG. 1. Fixedvolume chamber 215 has a fixed volume and may contain any liquid, suchas exudate from a tissue site, such as tissue site 105 in FIG. 1. Fixedvolume chamber 215 may be welded, screwed, glued, bolted, air-locksealed, or snapped onto filter housing 220.

Fixed volume chamber 215 includes inlet valve 240. Inlet valve 240 is anon-limiting example of inlet valve 140 in FIG. 1. As shown in FIG. 2,inlet valve 240 is centrally located at an end wall of fixed volumechamber 215. Also, inlet valve 240 and outlet valve 224 are each locatedalong a central longitudinal axis 290, which traverses the center ofpump 200.

Any liquid, such as exudate, may flow from a manifold, such as manifold145 in FIG. 1, into fixed volume chamber 215 via inlet valve 240. Theflow of liquid into fixed volume chamber 215 via inlet valve 240 isindicated by an arrow 242. Inlet valve 240 also restrains or preventsthe passage of liquid out of fixed volume chamber 215 at the point atwhich inlet valve 240 is located.

Any of a variety of valves may be used to achieve the functionality ofinlet valve 240. In one embodiment, top portion 246 of inlet valve 240is a duck bill valve. Inlet valve 240 may also be an umbrella valve,duckbill valve, ball valve, diaphragm valve, and any type of one-wayvalve.

Liquid flow into fixed volume chamber 215 is caused by the reducedpressure in fixed volume chamber 215. The reduced pressure in fixedvolume chamber 215 is caused by the reduced pressure transferred fromcompressible bellows 210 to fixed volume chamber 215. As compressiblebellows 210 is moved from a compressed position to an uncompressedposition, gas is transferred from fixed volume chamber 215 tocompressible bellows 210. As a result, reduced pressure is transferredto fixed volume chamber 215 from compressible bellows 210 in response toa movement of compressible bellows 210 from a compressed position to anuncompressed position. As compressible bellows 210 is moved from anuncompressed position to a compressed position, gas moves out ofcompressible bellows 210 via outlet valve 224. Suchcompression/expansion cycles may be repeated to apply a desired amountof reduced pressure to a tissue site, such as tissue site 105 in FIG. 1.

Referring to FIG. 3, compressible bellows 300, which is a non-limitingexample of bellows pump 200 in FIG. 2, is shown in accordance with anillustrative embodiment. In FIG. 3, compressible bellows 300 is shown intwo different positions in the range of positions that may be achievedby compressible bellows 300. In particular, compressible bellows 300 isshown in an uncompressed position 305 and a compressed position 310.Compressible bellows 300 has a greater volume in uncompressed position305 than in compressed position 310.

As compressible bellows 300 is compressed from uncompressed position 305to compressed position 310, the gas in compressible bellows 300 isexpelled through outlet valve 324, which is a non-limiting example ofoutlet valve 224 in FIG. 2. The volume of compressible bellows 300decreases as the compressible bellows 300 is compressed.

As compressible bellows 300 expands from compressed position 310 touncompressed position 305, gas does not enter compressible bellows 300via outlet valve 324 because outlet valve 324 allows air only to exitcompressible bellows 300. Instead, gas enters bellows pump from a fixedvolume chamber, such as fixed volume chamber 215 in FIG. 2, to whichcompressible bellows 300 is coupled. The volume of compressible bellows300 increases as compressible bellows 300 expands from compressedposition 310 to uncompressed position 305.

The expansion force necessary to expand compressible bellows 300 isprovided by an expansion or biasing force. The material from whichcompressible bellows 300 is composed is elastically deformed whencompressible bellows 300 is in compressed position 310. Elasticproperties of the material from which compressible bellows 300 iscomposed biases the corrugations included on compressible bellows 300 tomove away from one another such that compressible bellows 300 expands touncompressed position 305. As compressible bellows 300 expands, thesealed nature of the variable volume chamber results in a reducedpressure being created within the variable volume chamber. The reducedpressure may then be transmitted through a hydrophobic filter to a fixedvolume chamber, which, in turn, transmits the reduced pressure to atissue site.

Referring to FIG. 4, a portion of filter housing 420, which is anon-limiting example of filter housing 220 in FIG. 2, is shown inaccordance with an illustrative embodiment. Odor filter 431, which is anon-limiting example of odor filter 231 in FIG. 2, fits onto filterhousing 420 at a groove 432. Hydrophobic filter 434, which is anon-limiting example of hydrophobic filter 234 in FIG. 2, isultrasonically welded to filter housing 420 at a protrusion 439.However, as described above, hydrophobic filter 234 may be coupled tofilter housing 420 in a variety of ways. Odor filter 431 is sandwichedin between filter housing 420 and hydrophobic filter 434 at groove 432,and may or may not be independently attached to filter housing 420.

As indicated by arrows 443, gas, such as air, is permitted to flowthough hydrophobic filter 434 and odor filter 431, via a gap 445.However, hydrophobic filter 434 prevents liquid, such as exudate, frompassing through gap 445. Also, odor filter 431 prevents odor frompassing through gap 445.

Referring to FIG. 5, an interlocking seal between compressible bellows510, which is a non-limiting example of compressible bellows 210 in FIG.2, and filter housing 520, which is a non-limiting example of filterhousing 220 in FIG. 2, is shown in accordance with an illustrativeembodiment. The interlocking seal shown in FIG. 5 allows compressiblebellows 510 to be snapped onto filter housing 520, while maintaining anair-tight seal for the proper operation of the reduced pressuretreatment system. Compressible bellows 510 includes a snap protrusion530. Filter housing 520 includes an undercut 540 into which snapprotrusion 530 may be inserted. The large area of contact betweencompressible bellows 510 and filter housing 520, as indicated by a span550, assists in maintaining a proper seal between compressible bellows510 and filter housing 520.

Referring to FIG. 6, an interlocking seal between compressible bellows610, which is a non-limiting example of compressible bellows 210 in FIG.2, and filter housing 620, which is a non-limiting example of filterhousing 220 in FIG. 2, is shown in accordance with an illustrativeembodiment. Similar to the interlocking seal in FIG. 5, filter housing620 includes undercut 640 into which snap protrusion 630 of compressiblebellows 610 may be inserted. However, in contrast to FIG. 5, theillustrative embodiment of the interlocking seal in FIG. 6 shows thatcompressible bellows 610 includes ribs 655. Filter housing 620 alsoincludes indentations 660, into which ribs 655 may be inserted. The useof interlocking ribs 655 and indentations 660 may help create a tighterseal between compressible bellows 610 and filter housing 620.

Referring to FIG. 7, outlet valve 724, which is a non-limiting exampleof outlet valve 224 in FIG. 2, is shown in accordance with anillustrative embodiment. Outlet valve 724 is coupled to an end wall 730of compressible bellows 710, which is a non-limiting example ofcompressible bellows 210 in FIG. 2. End wall 730 may be made of metal,plastic, rubber, or any other material. In FIG. 7, end wall 730 may bewelded onto compressible bellows 710 at the spans indicated by spans735. However, end wall 730 may also be screwed, glued, bolted, air-locksealed, or snapped onto compressible bellows 710.

Gas, such as air, flows out of compressible bellows 710 as indicated byarrows 740. In particular, gas flows out of compressible bellows 710through gaps 741 and then passes through the space between outlet valveflaps 742 and 743 and end wall 730. However, because outlet valve flaps742 and 743 are only opened by the flow of gas out of compressiblebellows 710, gas cannot enter compressible bellows 710 through outletvalve 724. In FIG. 7, outlet valve 724 is an umbrella valve. However,outlet valve 724 may be any valve capable of allowing gas to pass out ofcompressible bellows 710 while restraining or preventing gas frompassing out of compressible bellows 710.

Referring to FIG. 8, a connection between end wall 830, which is anon-limiting example of end wall 730 in FIG. 7, and compressible bellows810, which is a non-limiting example of compressible bellows 710 in FIG.7, is shown in accordance with an illustrative embodiment. In contrastto FIG. 7, the illustrative embodiment of FIG. 8 shows a protrusion 840included on compressible bellows 810. End wall 830 also includes anindentation 850 into which protrusion 840 may be inserted. The use ofprotrusion 840 and indentation 850 may help create a tighter sealbetween compressible bellows 810 and end wall 830, as well as helpreduce the amount of welding necessary to couple compressible bellows810 to end wall 830.

Referring to FIG. 9, compressible bellows 910, which is a non-limitingexample of compressible bellows 210 in FIG. 2, is shown in accordancewith an illustrative embodiment. Compressible bellows 910 is coupled tofilter housing 920, which is a non-limiting example of filter housing220 in FIG. 2. In FIG. 9, end wall 930 of compressible bellows 910 doesnot include an outlet valve. Instead, compressible bellows 910 includesoutlet valves at the portions of compressible bellows 910 indicated bybrackets 940 and 945. In addition, compressible bellows 910 may includeone or more outlet valves around the perimeter of compressible bellows910 indicated by brackets 940 and 945. Additional details regarding theoutlet valves at the portion of compressible bellows 910 indicated bybrackets 940 and 945 is described in FIGS. 10-13 below.

Turning now to FIG. 10, an umbrella outlet valve that is part ofcompressible bellows 1010, which is a non-limiting example ofcompressible bellows 910 in FIG. 9, is shown in accordance with anillustrative embodiment. The outlet valve includes a flap 1025. Filterhousing 1020, which is a non-limiting example of filter housing 920 inFIG. 9, includes a gap 1027. Upon moving compressible bellows 1010 froman uncompressed position to a compressed position, gas flows out ofcompressible bellows through gap 1027 as indicated by arrow 1029. Theflow of gas lifts flap 1025 into open position 1035, as indicated by anarrow 1037, thereby allowing the passage of gas out of compressiblebellows 1010. When air is not flowing out of compressible bellows 1010,such as when compressible bellows 1010 is moving from a compressedposition to an uncompressed position, flap 1025 is in contact withfilter housing 1020 such that gas may not flow into compressible bellows1010.

In this embodiment, compressible bellows 1010 may also have protrusion1040, which fits into indentation 1045 of filter housing 1020. Thefitting of protrusion 1040 into indentation 1045 helps to maintain asnap fit between compressible bellows 1010 and filter housing 1020.

Referring to FIG. 11, an outlet valve located on compressible bellows1110 at the general portion of compressible bellows 1110 that contactsfilter housing 1120 is shown in accordance with an illustrativeembodiment. Compressible bellows 1110 is a non-limiting example ofcompressible bellows 910 in FIG. 9, and filter housing 1120 isanon-limiting example of filter housing 920 in FIG. 9.

Upon compression of compressible bellows 1110 from an uncompressedposition to a compressed position, gas attempts to flow out ofcompressible bellows 1110 through gap 1127 as indicated by arrow 1129.The gas encounters flap 1125, which includes a rib 1135. The strength ofrib 1135, which may depend on the thickness or material of rib 1135,determines the amount of force that must be exerted by the gas in orderto bend flap 1125 such that air can escape compressible bellows 1110.Thus, the strength of rib 1135 also determines the amount of pressurethat is created by compressible bellows 1110, and which is ultimatelytransferred to a tissue site, such as tissue site 105 in FIG. 1.

Referring to FIG. 12, the outlet valve of FIG. 11 in an open position isshown in accordance with an illustrative embodiment. The flow of gas,which is indicated by arrow 1229, has exerted sufficient force upon flap1225 of compressible bellows 1210 such that flap 1225 has been bent toallow for the release of gas from compressible bellows 1210. Inparticular, the force exerted by the flow of gas is sufficient toovercome the strengthening force of rib 1235.

Referring to FIG. 13, an outlet valve located on a side wall of bellowpump 1310, which is a non-limiting example of compressible bellows 1110and 1210 in FIGS. 11 and 12, respectively, is shown in accordance withan illustrative embodiment. FIG. 13 shows flap 1325, which is anon-limiting example of flaps 1125 and 1225 in FIGS. 11 and 12,respectively. FIG. 13 also shows rib 1335, which is a non-limitingexample of ribs 1135 and 1235 in FIGS. 11 and 12, respectively. Asdescribed above, rib 1335 may be used to adjust the force required toopen flap 1325, thereby varying the amount of pressure that may becreated by bellow pump 1310.

Referring to FIG. 14, reduced pressure treatment system 1400, which isencased by a casing having a top casing portion 1402 and a bottom casingportion 1404, is shown in accordance with an illustrative embodiment.Reduced pressure treatment system 1400 compressible bellows 1410, filterhousing 1420, odor filter 1431, hydrophobic filter 1434, an variablevolume chamber 1415.

FIG. 14 shows the orientation of the different components of reducedpressure treatment system 1400 relative to one another. Compressiblebellows 1410, which is a non-limiting example of compressible bellows210 in FIG. 2, may be inserted into top casing portion 1402. Top casingportion also includes a grip 1403. Grip 1403 may be composed of rubber,plastic, or any other material capable of improving tactile grip on topcasing portion 1402.

The cross-sectional shape of compressible bellows 1410 is an oval. Inparticular, compressible bellows 1410 has an elongated middle portion1412 and rounded end portions 1414. The cross sectional shape ofcompressible bellows 1410 allows compressible bellows 1410 to fit intotop casing portion 1402. The cross sectional shape of compressiblebellows 1410 may vary depending on the shape of the casing for thereduced pressure treatment system.

Compressible bellows 1410 couples to filter housing 1420, which is anon-limiting example of filter housing 220 in FIG. 2. Filter housing1420 includes a grid mesh 1425 through which gas may flow.

Odor filter 1431 and hydrophobic filter 1434, which are non-limitingexamples of odor filter 231 and hydrophobic filter 234 in FIG. 2,respectively, fit into filter housing 1420 as described in the previousFigures. Fixed volume chamber 1415, which is anon-limiting example offixed volume chamber 215 in FIG. 2, couples to filter housing 1420.Fixed volume chamber 415 may be inserted into bottom casing portion1404.

Top casing portion 1402 and bottom casing portion 1404 may be composedof any material. For example, top casing portion 1402 and bottom casingportion 1404 may be composed of materials that are suitable to protectthe inner components of reduced pressure treatment system 1400.Non-limiting examples of the material from which top casing portion 1402and bottom casing portion 1404 may be composed include plastic, metal,or rubber.

Referring to FIG. 15, compressible bellows 1510 and 1512, each of whichis a non-limiting example of compressible bellows 210 in FIG. 2, isshown in accordance with an illustrative embodiment. Compressiblebellows 1510 and 1512 can replace the oval compressible bellows 1410 inFIG. 14. Thus, compressible bellows 1510 and 1512 may be configured tobe inserted into atop casing portion, such as top casing portion 1402 inFIG. 14. Each of compressible bellows 1510 and 1512 are coupled tofilter housing 1520, which is a non-limiting example of filter housing1420 in FIG. 14.

The use of two compressible bellows 1510 and 1512 allows the reducedpressure treatment system in which compressible bellows 1510 and 1512are employed to continue functioning in the event that one of thecompressible bellows leaks or otherwise fails. The use of compressiblebellows 1510 and 1512 may also improve manufacturing efficiency in theconstruction of a reduced pressure treatment system. For example, themanufacture of compressible bellows 1510 and 1512 having a circularcross-section may be easier than the manufacture of a singlecompressible bellows having an elongated cross section that allows thesingle compressible bellows to fit inside top casing portion 1402.

Referring to FIG. 16, reduced pressure treatment system 1600, which is anon-limiting example of reduced pressure treatment system 1400 in FIG.14, is shown in accordance with an illustrative embodiment. Reducedpressure treatment system 1600 shows reduced pressure treatment system1400 when reduced pressure treatment system 1400 has been assembled. Inreduced pressure treatment system 1600, top and bottom casing portions1602 and 1604 encase the various components of reduced pressuretreatment system 1600, such as a compressible bellows, filter housing,odor filter, hydrophobic filter, and fixed volume chamber. Top andbottom casing portions 1602 and 1604 are non-limiting examples of topand bottom casing portions 1402 and 1404 in FIG. 14, respectively.

Reduced pressure treatment system 1600 also includes visual indicators1608. Visual indicators 1608 indicate to a user an amount of reducedpressure to be delivered to a tissue site, such as tissue site 105 inFIG. 1. In particular, the lines of visual indicators 1608 indicate thedegree to which top casing portion 1602 has been compressed relative tobottom casing portion 1604, and therefore also indicates the degree towhich the one or more compressible bellows inside top casing portion1602 has been compressed. Using visual indicators 1608, a user canconsistently deliver a desired amount of reduced pressure to a tissuesite. The visual indicators 1608 may be located on either or both of thetop casing portion 1602 or the bottom casing portion 1604.

Reduced pressure treatment system 1600 also includes an end cap 1612.End cap 1612 fits onto bottom casing portion 1604 and may be coupled todelivery tube 1635, which is a non-limiting example of delivery tube 135in FIG. 1. Additional details regarding end cap 1612 will be describedin FIGS. 19 and 20 below.

Referring to FIGS. 17 a, 17 b, and 17 c, a reduced pressure apparatus1700 includes a top casing portion 1702 and a bottom casing portion1704, each of which have a substantially cylindrical shape. The bottomcasing portion 1704 has a larger diameter than the top casing portion1702 such that the top casing portion 1702 can be slidingly received bythe bottom casing portion 1704. The top casing portion 1702 iscompressible into a plurality of positions relative to the bottom casingportion 1704, including the uncompressed position shown in FIG. 17 a,the fully compressed position shown in FIG. 17 b, and a plurality ofintermediate positions (which are partially compressed) between theuncompressed position and the fully compressed position. The top casingportion 1702 may be slidable into the bottom casing portion 1704 alongan axis substantially parallel to bidirectional arrow 1706.

The top casing portion 1702 includes an indicator 1710. The indicator1710 is disposed on a region of the top casing portion 1702 that isadjacent the bottom casing portion 1704 when the reduced pressureapparatus 1700 is in the uncompressed position. The indicator 1710 isvisible when the top casing portion 1702 is in the uncompressed positionbut is obscured, or not visible, when the top casing portion 1702 is inthe fully compressed position. The indicator 1710 may also be visible inat least one of the intermediate positions between the compressedposition and the uncompressed position.

In another embodiment, the visual indicators described herein may beprovided to indicate when the reduced pressure apparatus is in a fullycompressed position prior to a first use of the reduced pressureapparatus. Such an indicator would assist in ensuring that the reducedpressure apparatus is fully charged or that the reduced pressureapparatus is not being reused on another patient.

The indicator 1710 may be any indicia or markings that is capable ofindicating a position of the top casing portion 1702 relative to thebottom casing portion 1704. In the embodiment illustrated in FIG. 17,the indicator 1710 is a color band or color strip that is a contrastingcolor to the color of adjacent portions of the top casing portion 1702.The color of the indicator 1710 may be any color or multiple colors.Alternatively, the indicator 1710 may not be a solid color band, butinstead may be an outline of a band or strip. Similarly, the indicator1710 may be a region on the top casing portion 1702 that includesstriping, letters, numbers, symbols, or other indicia. In FIG. 17 a, theindicator 1710 is partially disposed around the circumference of the topcasing portion 1702, but the indicator 1710 may also be disposed aroundan entire circumference of the top casing portion 1702.

In another embodiment, the indicator 1710 is a tactile indicator thathas a texture that is different from the texture of the remainder of thetop casing portion 1702. In this embodiment, a visually-impaired usermay touch the top casing portion 1702 to determine the position of thereduced pressure apparatus 1700. When the reduced pressure apparatus1700 is in the uncompressed position, the user will be able to feel theindicator 1710 and thereby be notified that the system 1710 is in theuncompressed position.

In operation, the reduced pressure apparatus 1700 is manually actuatedto generate a reduced pressure at an outlet 1716. Manual actuation ofthe reduced pressure apparatus 1700 is accomplished by a user manuallycompressing the top casing portion 1702 within the bottom casing portion1704 such that the top casing portion 1702 is placed in the fullycompressed position or at least one of the intermediate positions. Theinternal mechanism for generating reduced pressure may be any suitablemechanism including, without limitation, those mechanisms that have beendescribed herein. In at least one embodiment, the mechanism by whichreduced pressure is generated involves the reduction in volume of andexpulsion of gas from a chamber (not shown), and then subsequently asealing of the chamber and expansion in volume of the chamber. As thevolume of the sealed chamber increases, the reduced pressure isgenerated within the chamber. The reduction in volume of the chamber maybe accomplished by compressing the top casing portion 1702 within thebottom casing portion 1704.

FIG. 17 c shows the reduced pressure apparatus 1700 as part of a reducedpressure therapy system 1701. The reduced pressure apparatus 1700 isfluidly coupled to a dressing 1720 via a conduit 1735 that deliversreduced pressure. A sealing member 1750 covers the tissue site 105 of apatient 1707. The sealing member 1750 has an aperture in which theconnection member 1755 is disposed. The conduit 1735 is in fluidcommunication with a sealed space 1751 that is covered by the sealingmember 1750 via the connection member 1755. The dressing 1720 may alsoinclude a manifold in the sealed space 1751. Reduced pressure may bedelivered to the sealed space 1751 by the reduced pressure apparatus1700.

When the top casing portion 1702 is placed in the fully compressedposition, the indicator 1710 is no longer visible since the portion ofthe top casing portion 1702 on which the indicator 1710 lies is hiddenfrom view within the bottom casing portion 1704. When fully compressed,reduced pressure is delivered to an outlet 1716, and this reducedpressure is available for delivery the tissue site 105. As time passes,air leakage from the sealed space 1751, as well as other factors thatcause local increases in pressure at the tissue site 105, results in amovement of the top casing portion 1702 toward the uncompressedposition. As the top casing portion 1702 moves closer to theuncompressed position, the indicator 1710 begins to become exposed.Since movement toward the uncompressed position indicates a loss ofreduced pressure, or a loss of remaining capacity to generate reducedpressure, the presence of the indicator 1710 communicates to a user thata partial discharge of the reduced pressure apparatus 1700 has occurred.The presence of the visual indicator 1710 further communicates to theuser the approaching need to re-charge or re-compress the reducedpressure apparatus 1700 back into a compressed position in order todeliver or maintain a therapeutic reduced pressure at the tissue site105. If the rate of discharge of the reduced pressure apparatus 1700 isconstant, the initial presence of the indicator 1710 at an intermediateposition may be determinative of the amount of time remaining duringwhich reduced pressure will be generated or applied.

The indicator 1710 includes a height, H, in a direction parallel to thedirection of travel of the top casing portion 1702 indicated bybidirectional arrow 1706. The height, H, is determinative of when theindicator 1710 will first be exposed during operation of the reducedpressure apparatus 1700. As the reduced pressure apparatus 1700discharges and the top casing portion moves from the fully compressedposition to the uncompressed position, an indicator having a greaterheight will be visible earlier than an indicator having a lesser height.

As explained above, the indicator 1710 is capable of communicating theapproaching cessation of reduced pressure generation or delivery, and insome cases, the amount of time left until such cessation. The indicator1710 may also be capable of alerting a user that a particular amount ofreduced pressure is being applied. In one example, the compression ofthe top casing portion 1702 into a compressed position decreases thevolume of a variable volume chamber located in the bottom casing portion1704. The reduced pressure in the variable volume chamber in the bottomcasing portion 1704 may decrease as the top casing portion 1702 movestoward an uncompressed position. As the top casing portion 1702 movesthrough the intermediate positions toward the uncompressed position, theindicator 1710 becomes more exposed. The relative positioning of the topcasing portion 1702 and the bottom casing portion 1704 at the time theindicator 1710 is first exposed, and at times subsequent to the firstexposure, may be indicative of a particular reduced pressure, which maybe communicated to the user by the presence and positioning of theindicator 1710.

Referring to FIG. 18, a reduced pressure treatment system 1800 is shownaccording to an illustrative embodiment. The reduced pressure treatmentsystem 1800, in contrast to the reduced pressure apparatus 1700,includes indicia or markings 1810. Although each of the markings 1810are shown to be circles, each of the markings 1810 may have any shape,such as a square, a triangle, or other polygon. Alternatively, themarkings 1810 may be lines, symbols, numbers, or letters, or somecombination thereof. In the embodiment in which the markings 1810 arelines, the lines may be substantially perpendicular to the axis alongwhich the top casing portion 1802 is compressible. Although theplurality of markings 1810 includes three markings, the plurality ofmarkings 1810 may include any number of markings. When the top casingportion 1802 is compressed into the bottom casing portion 1804, all or aportion of the plurality of markings 1810 are hidden from view.

As the top casing portion 1802 moves toward an uncompressed position,each of the plurality of markings 1810 may gradually become exposed. Forexample, as the top casing portion 1802 moves toward an uncompressedposition from a fully compressed position, the marking 1812 may firstbecome exposed. The marking 1814 may then become exposed as the topcasing portion 1802 moves further toward the uncompressed position.Finally, the marking 1816 may then become exposed as the top casingportion 1802 moves into a fully uncompressed position. Each of theplurality of markings 1810 may have a different color or texture toprovide a user with color or tactile-aided indications of the positionof the top casing portion 1802.

The user may be alerted to a state of the reduced pressure treatmentsystem 1800 based on the number of the plurality of markings 1810 thatare exposed to the user. For example, the more of the plurality ofmarkings 1810 that are exposed, the more urgent may be the need for auser to perform an action to the reduced pressure treatment system 1800,such as to compress the top casing portion 1802 into a compressedposition to maintain a reduced pressure that is being generated ordelivered by the reduced pressure treatment system 1800.

Referring to FIG. 19, a process that may be implemented by amanually-actuated pump, such as pump 102 in FIG. 1 or any otherillustrative embodiment of the reduced pressure treatment systemdescribed above, is shown in accordance with an illustrative embodiment.

The process compresses a variable volume chamber having a variablevolume from an uncompressed position to a compressed position (step1905). The process determines whether the compressed position yields athreshold level of reduced pressure as indicated by an indicator, suchas visual indicators 1608 in FIG. 16 (step 1910). If the processdetermines that the compressed position does not yield a threshold levelof reduced pressure as indicated by an, indicator, the process furthercompresses or expands the variable volume chamber (step 1915). Theprocess then returns to step 1910.

If the process determines that the compressed position yields athreshold level of reduced pressure as indicated by an indicator, theprocess may then expand the variable volume chamber from the compressedposition to the uncompressed position (step 1920). The process transfersreduced pressure from the variable volume chamber to a fixed volumechamber (step 1925). The process may then transfer the reduced pressureto a tissue site via a manifold and delivery tube (step 1930).

The flowcharts and block diagrams in the different depicted embodimentsillustrate the architecture, functionality, and operation of somepossible implementations of the apparatus and methods. In somealternative implementations, the function or functions noted in theblock may occur out of the order noted in the figures. For example, insome cases, two blocks shown in succession may be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved.

The illustrative embodiments described herein separate the chambers inwhich exudates and other liquids are collected from thereduced-pressure-generating chamber. Thus, the compressible pumps arecapable of being re-charged (i.e. the flexible bellows can bere-depressed) even when liquids are present in the fixed volume chamber.When the fixed volume chamber becomes completely full of exudate orother liquids, the fixed volume chamber may then be emptied beforeadditional reduced pressure may be applied by the compressible pump.Also, the illustrative embodiments, unlike traditionalmanually-activated systems, are capable of delivering a measured andconsistent amount of pressure to a tissue site during a particularreduced pressure treatment cycle. The illustrative embodiments arefurther capable of consistently repeating the targeted pressure eachtime the compressible pump is recharged. These pressure deliverycapabilities exist regardless of the orientation or location of thefixed volume chamber.

The illustrative embodiments are also capable of alerting a user as tothe need to perform an action on a reduced pressure source. For example,the illustrative embodiments may include a visual indicator that, whenexposed, alerts a user that the reduced pressure source needs to becompressed or otherwise charged.

We claim:
 1. A reduced pressure apparatus comprising: a first casingportion; a second casing portion slidably coupled to the first casingportion such that the first casing portion is compressible into aplurality of positions relative to the second casing portion to delivera reduced pressure to a tissue site, the plurality of positionsincluding a fully compressed position and an uncompressed position; andan indicator disposed on at least one of the first casing portion andthe second casing portion, the indicator being exposed when the firstcasing portion is in the fully uncompressed position and beingsubstantially obscured when the first casing portion is in the fullycompressed position.
 2. The reduced pressure apparatus of claim 1,wherein the indicator is located on a region of the first casing portionthat is adjacent the second casing portion when the first casing portionis in the uncompressed position.
 3. The reduced pressure apparatus ofclaim 2, wherein the indicator is a strip that is at least partiallycircumferentially disposed around the first casing portion.
 4. Thereduced pressure apparatus of claim 3, wherein the strip is disposedaround an entire circumference of the first casing portion.
 5. Thereduced pressure apparatus of claim 3, wherein a color of the strip isdifferent than a color of the remainder of the first casing portion. 6.The reduced pressure apparatus of claim 1, wherein the indicator is aplurality of markings.
 7. The reduced pressure apparatus of claim 6,wherein the plurality of markings are located along an axis, wherein thefirst casing portion is compressible along the axis.
 8. The reducedpressure apparatus of claim 7, wherein the plurality of markings is aplurality of circles.
 9. The reduced pressure apparatus of claim 7,wherein the plurality of markings is a plurality of lines, each of thelines being substantially perpendicular to the axis.
 10. The reducedpressure apparatus of claim 6, wherein each of the plurality of markingshave a different color.
 11. The reduced pressure apparatus of claim 1,wherein the indicator has a texture that is different than a texture ofthe remainder of the first casing portion.
 12. The reduced pressureapparatus of claim 1, wherein the reduced pressure apparatus is operableto deliver a reduced pressure when the first casing portion is in thefully compressed position.
 13. The reduced pressure apparatus of claim1, wherein the indicator is exposed when the first casing portion is inan intermediate position between the fully compressed position and thefully uncompressed position.
 14. A reduced pressure therapy system foradministering reduced pressure treatment to a tissue site, the systemcomprising: a manifold adapted to be positioned at the tissue site; areduced pressure source in fluid communication with the manifold todeliver a reduced pressure to the manifold, the reduced pressure sourcecomprising: a top casing portion; a bottom casing portion slidablycoupled to the top casing portion such that the top casing portion ispositionable in a plurality of positions relative to the bottom casingportion to deliver a reduced pressure to a tissue site, the plurality ofpositions including a fully compressed position, a fully uncompressedposition, and a plurality of intermediate positions between the fullycompressed position and the fully uncompressed position; and anindicator disposed on at least one of the top casing portion and thebottom casing portion, the indicator being exposed when the top casingportion is in at least one of the plurality of intermediate positionsand being substantially obscured when the first casing portion is in thefully compressed position; and a sealing member adapted to cover thetissue site to form a sealed space between the sealing member and thetissue site, the sealed space in fluid communication with the reducedpressure source.
 15. The reduced pressure therapy system of claim 14,wherein the top casing portion moves toward a fully uncompressedposition as gas leaks from the sealed space.
 16. The reduced pressuretherapy system of claim 14, wherein the reduced pressure source isoperable to deliver the reduced pressure to the sealed space when thetop casing portion is in at least one of the plurality of intermediatepositions.
 17. The reduced pressure therapy system of claim 14, whereinthe indicator is located on a region of the top casing portion that isadjacent the bottom casing portion when the top casing portion is in thefully uncompressed position.
 18. The reduced pressure therapy system ofclaim 14, wherein the indicator is a strip that is at least partiallycircumferentially disposed around the top casing portion.
 19. A reducedpressure apparatus comprising: a substantially cylindrical top casingportion; a substantially cylindrical bottom casing portion having alarger diameter than the substantially cylindrical top casing portion,the substantially cylindrical top casing portion slidably received bythe substantially cylindrical bottom casing portion such that thesubstantially cylindrical top casing portion is positionable in aplurality of positions relative to the substantially cylindrical bottomcasing portion, the plurality of positions including a fully compressedposition, an uncompressed position, and a plurality of intermediatepositions between the fully compressed position and the uncompressedposition, the reduced pressure apparatus operable to deliver a reducedpressure as the substantially cylindrical top casing portion moves fromthe fully compressed position to the uncompressed position; and a colorstrip disposed on the substantially cylindrical top casing portion suchthat the color strip is exposed when the substantially cylindrical topcasing portion is in the uncompressed position and is obscured when thesubstantially cylindrical top casing portion is in the fully compressedposition.
 20. The reduced pressure apparatus of claim 19, wherein thecolor strip is exposed when the substantially cylindrical top casingportion is in at least one of the plurality of intermediate positions.